Generally, vertical cavity surface emitting lasers (VCSELs) and resonant cavity light emitting diodes (RC-LEDs) refer to light emitting devices, which include a resonator having a multi-quantum well (MQW) structure and placed between two distributed Bragg reflectors (hereinafter, referred to as “DBR(s)”) having a multilayer thin film structure to emit light with a gain by current injection. Since these light emitting devices generally perform surface emission in a circular radiation pattern, they can be easily arranged in fabrication of optical systems and can be assembled at low cost.
The DBR structure of conventional vertical cavity surface emitting lasers (VCSEL) and resonant cavity light emitting diodes (RC-LED) is formed by adjusting a composition ratio of a compound semiconductor represented by AlxGa(1-x)As (0≦x≦1). Various types of thin films can be obtained through adjustment of the composition ratio of the compound semiconductor, and a suitable low refractive index layer and high refractive index layer can be selected from among these thin films in consideration of a difference in index of refraction and band-gap.
However, since such a typical DBR structure is formed by a high quality thin film growth method such as molecular beam epitaxy (MBE), metal organic chemical vapor deposition (MOCVD), and the like, there are problems of constraints in selection of substrates and in adjustment of the index of refraction. Further, since an index contrast between the low refractive index layer and the high refractive index layer is small, a number of layers (about 30 pairs or more) are stacked in order to achieve high reflectivity, thereby causing increase in thickness of the structure. Moreover, it is difficult to form the DBR structure in a desired shape.